Filtering in EJ2 TypeScript Combo box control
2 May 202319 minutes to read
The ComboBox has built-in support to filter data items when allowFiltering is enabled. The filter operation starts as soon as you start typing characters in the component.
To display filtered items in the popup, filter the required data and return it to the ComboBox via updateData method by using the filtering event.
The following sample illustrates how to query the data source and pass the data to the ComboBox through the updateData method in filtering event.
import { ComboBox, FilteringEventArgs } from '@syncfusion/ej2-dropdowns';
import { DataManager, Query } from '@syncfusion/ej2-data';
let searchData: { [key: string]: Object; }[] = [
{ Index: "s1", Country: "California" }, { Index: "s2", Country: "Florida" },
{ Index: "s3", Country: "Alaska" }, { Index: "s4", Country: "Georgia" }
];
let filter: ComboBox = new ComboBox({
//set the search data to dataSource property
dataSource: searchData,
//map the appropriate columns to fields property
fields: { text: "Country", value: "Index" },
//set the placeholder to ComboBox input
placeholder:"Select a country",
//enable to filtering in ComboBox
allowFiltering: true,
//sort the resulted items
sortOrder: 'Ascending',
//Bind the filter event
filtering: function (e: FilteringEventArgs) {
let query = new Query();
//frame the query based on search string with filter type.
query = (e.text != "") ? query.where("Country", "startswith", e.text, true) : query;
//pass the filter data source, filter query to updateData method.
e.updateData(searchData, query);
}
});
filter.appendTo('#comboelement');<!DOCTYPE html>
<html lang="en">
<head>
<title>Essential JS 2 ComboBox</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="description" content="Typescript UI Controls" />
<meta name="author" content="Syncfusion" />
<link href="styles.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-base/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-inputs/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
<script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>
<body>
<div id='loader'>LOADING....</div>
<div id='container' style="margin:50px auto 0; width:250px;">
<br>
<input type="text" id='comboelement' />
</div>
</body>
</html>Limit the minimum filter character
When filtering the list items, you can set the limit for character count to raise remote request and fetch filtered data on the ComboBox. This can be done by manual validation within the filter event handler.
In the following example, the remote request does not fetch the search data until the search key contains three characters.
import { ComboBox, FilteringEventArgs } from '@syncfusion/ej2-dropdowns';
import { Query, DataManager, ODataV4Adaptor } from '@syncfusion/ej2-data';
let searchData: DataManager = new DataManager({
url: 'https://services.odata.org/V4/Northwind/Northwind.svc/Customers',
adaptor: new ODataV4Adaptor,
crossDomain: true
});
let filter: ComboBox = new ComboBox({
dataSource: searchData,
query: new Query().select(['ContactName', 'CustomerID']).take(6),
// map the appropriate column
fields: { text: 'ContactName', value: 'CustomerID' },
// set placeholder to ComboBox input element
placeholder:"Select a customer",
// set true to allowFiltering for enable filtering supports
allowFiltering: true,
//sort the resulted items
sortOrder: 'Ascending',
//bind the filtering event handler
filtering: (e: FilteringEventArgs) => {
// load overall data when search key empty.
if(e.text == '') e.updateData(searchData);
else{
// restrict the remote request until search key contains 3 characters.
if (e.text.length < 3) { return; }
let query: Query = new Query().select(['ContactName', 'CustomerID']);
query = (e.text !== '') ? query.where('ContactName', 'startswith', e.text, true) : query;
e.updateData(searchData, query);
}
}
});
filter.appendTo('#comboelement');<!DOCTYPE html>
<html lang="en">
<head>
<title>Essential JS 2 ComboBox</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="description" content="Typescript UI Controls" />
<meta name="author" content="Syncfusion" />
<link href="styles.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-base/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-inputs/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
<script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>
<body>
<div id='loader'>LOADING....</div>
<div id='container' style="margin:50px auto 0; width:250px;">
<br>
<input type="text" id='comboelement' />
</div>
</body>
</html>Change the filter type
While filtering, you can change the filter type to contains, startsWith, or endsWith for string type within the filter event handler.
In the following examples, data filtering is done with endsWith type.
import { ComboBox, FilteringEventArgs } from '@syncfusion/ej2-dropdowns';
import { Query, DataManager, ODataV4Adaptor } from '@syncfusion/ej2-data';
let searchData: DataManager = new DataManager({
url: 'https://services.odata.org/V4/Northwind/Northwind.svc/Customers',
adaptor: new ODataV4Adaptor,
crossDomain: true
});
let filter: ComboBox = new ComboBox({
dataSource: searchData,
query: new Query().select(['ContactName', 'CustomerID']).take(6),
// map the appropriate column
fields: { text: 'ContactName', value: 'CustomerID' },
// set placeholder to ComboBox input element
placeholder:"Select a customer",
//set the height of the popup element
popupHeight: "250px",
//sort the resulted items
sortOrder: 'Ascending',
// set true to allowFiltering for enable filtering supports
allowFiltering: true,
//bind the filtering event handler
filtering: (e: FilteringEventArgs) => {
// load overall data when search key empty.
if(e.text == '') e.updateData(searchData);
else{
let query: Query = new Query().select(['ContactName', 'CustomerID']);
// change the type of filtering to endswith filtering
query = (e.text !== '') ? query.where('ContactName', 'endswith', e.text, true) : query;
e.updateData(searchData, query);
}
}
});
filter.appendTo('#comboelement');<!DOCTYPE html>
<html lang="en">
<head>
<title>Essential JS 2 ComboBox</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="description" content="Typescript UI Controls" />
<meta name="author" content="Syncfusion" />
<link href="styles.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-base/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-inputs/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
<script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>
<body>
<div id='loader'>LOADING....</div>
<div id='container' style="margin:50px auto 0; width:250px;">
<br>
<input type="text" id='comboelement' />
</div>
</body>
</html>Case sensitive filtering
Data items can be filtered either with or without case sensitivity using the DataManager. This can be done by passing the fourth optional parameter of the where clause.
The following example shows how to perform case-sensitive filter.
import { ComboBox, FilteringEventArgs } from '@syncfusion/ej2-dropdowns';
import { Query, DataManager, ODataV4Adaptor } from '@syncfusion/ej2-data';
// defined the dataManager
let searchData: DataManager = new DataManager({
url: 'https://services.odata.org/V4/Northwind/Northwind.svc/Customers',
adaptor: new ODataV4Adaptor,
crossDomain: true
});
let filter: ComboBox = new ComboBox({
dataSource: searchData,
query: new Query().select(['ContactName', 'CustomerID']).take(6),
// map the appropriate column
fields: { text: 'ContactName', value: 'CustomerID' },
// set placeholder to ComboBox input element
placeholder:"Select a customer",
// set true to allowFiltering for enable filtering supports
allowFiltering: true,
//sort the resulted items
sortOrder: 'Ascending',
//set the height of the popup element
popupHeight: "250px",
//bind the filtering event handler
filtering: (e: FilteringEventArgs) => {
// load overall data when search key empty.
if(e.text == '') e.updateData(searchData);
else{
let query: Query = new Query().select(['ContactName', 'CustomerID']);
//enable the case sensitive filtering by passing false to 4th parameter.
query = (e.text !== '') ? query.where('ContactName', 'startswith', e.text, false) : query;
e.updateData(searchData, query);
}
}
});
filter.appendTo('#comboelement');<!DOCTYPE html>
<html lang="en">
<head>
<title>Essential JS 2 ComboBox</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="description" content="Typescript UI Controls" />
<meta name="author" content="Syncfusion" />
<link href="styles.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-base/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-inputs/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
<script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>
<body>
<div id='loader'>LOADING....</div>
<div id='container' style="margin:50px auto 0; width:250px;">
<br>
<input type="text" id='comboelement' />
</div>
</body>
</html>Diacritics Filtering
The ComboBox supports diacritics filtering which will ignore the diacritics and makes it easier to filter the results in international characters lists when the ignoreAccent is enabled.
In the following sample,data with diacritics are bound as dataSource for ComboBox.
import { ComboBox } from '@syncfusion/ej2-dropdowns';
// create local data
let data: string[] = [
'Aeróbics',
'Aeróbics en Agua',
'Aerografía',
'Aeromodelaje',
'Águilas',
'Ajedrez',
'Ala Delta',
'Álbumes de Música',
'Alusivos',
'Análisis de Escritura a Mano'];
// initialize ComboBox component
let comboObj: ComboBox = new ComboBox({
//set the local data to dataSource property
dataSource: data,
// set the placeholder to ComboBox input element
placeholder: 'e.g: aero',
// enabled the ignoreAccent property for ignore the diacritics
ignoreAccent: true,
// set true for enable the filtering support.
allowFiltering: true
});
comboObj.appendTo('#comboelement');<!DOCTYPE html>
<html lang="en">
<head>
<title>Essential JS 2 ComboBox</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="description" content="Typescript UI Controls" />
<meta name="author" content="Syncfusion" />
<link href="styles.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-base/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-inputs/styles/material.css" rel="stylesheet" />
<link href="https://cdn.syncfusion.com/ej2/27.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
<script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>
<body>
<div id='loader'>LOADING....</div>
<div id='container' style="margin:50px auto 0; width:250px;">
<br>
<input type="text" id='comboelement' />
</div>
</body>
</html>